1. Field of the Invention
This invention relates to a hand-held, portable labelling device having a printing apparatus and an inking roller loosely mounted on a journal pivot pin of a pivoting lever. Upon activation of the labelling device, the inking roller inks the printing apparatus and, during the inking procedure, the inking roller, along with the pivoting lever to which it is mounted, is moved out of its idle position by the printing apparatus. The pivoting lever and inking roller are returned to the idle position by the force of a spring acting thereon.
2. Background Information
One such manual labelling device is disclosed in German Patent No. 28 57 834 C2. In this manual labelling device, there is an elastic retaining element in the shape of a circular arc, for axially securing the inking roller on the journal pivot pin. The elastic retaining element engages a groove on the end of the inking roller. As the pivoting lever moves back-and-forth during a labelling cycle, the groove on the inking roller moves along this retaining element, so that the inking roller cannot be displaced axially. The inking roller is thus prevented from sliding off the journal pivot pin. To change the inking roller, the retaining element is raised out of the groove, against the force of a spring, thus allowing the inking roller to be axially removed from the journal pivot pin, and replaced by a new inking roller.
One serious disadvantage of the arrangement described above is that very strict requirements are necessary for precise manufacturing of the retaining element In this regard, the shape of the retaining element must essentially correspond exactly to the circular arc executed by the inking roller in its back-and-forth movement. The inking roller must also essentially be positioned precisely on this circular arc in its idle position, which is naturally quite difficult with such spring-loaded configurations. If these requirements are not completely satisfied, problems and malfunctions will almost inevitably occur in the manual labelling device. For example, the pivoting lever with the inking roller can jam on the retaining element. Also, the retaining element may not always be engaged with the groove of the inking roller, in which instance the inking roller may slide axially off the journal pivot pin or, even more likely, the inking roller can become jammed laterally next to the groove underneath the retaining element.
In addition to these functional disadvantages on known inking roller mountings, it is usually very unfavorable that the inking roller itself must have a groove which matches the inking roller mounting. This particular configuration of the inking roller naturally results in higher costs for the manufacture of such a roller. Further, since such rollers are subject to wear and have to be replaced regularly, such rollers are therefore a relatively expensive disposable piece. Moreover, such a configuration of the inking roller also tends to make the inking roller asymmetrical, so that while the labelling device is being operated, the operator is forced to worry about the proper orientation of the device. Furthermore, this known configuration also takes up additional space in the axial direction, because the inking roller cannot perform the task for which it is intended in the vicinity of the groove, namely the inking of the printing apparatus. Thus, a roller assembly having such a groove needs to be wider than a roller assembly which would not require such a groove, and therefore, the entire manual labelling device needs to be made wider and heavier.